Walk auxiliary declarations when gathering stored properties

Make sure we walk auxiliary declarations when gathering stored
properties. This ensures that we will get any stored properties
introduced by peer macros.

Fixes rdar://108534298.

Author: DougGregor

lib/Sema/TypeCheckStorage.cpp

@@ -169,14 +169,23 @@ static void computeLoweredStoredProperties(NominalTypeDecl *decl,
 static void enumerateStoredPropertiesAndMissing(
     NominalTypeDecl *decl,
     IterableDeclContext *implDecl,
-    llvm::function_ref<void(VarDecl *)> addStoredProperty,
+    llvm::function_ref<void(VarDecl *)> _addStoredProperty,
     llvm::function_ref<void(MissingMemberDecl *)> addMissing) {
+  // Add a variable as a stored properties.
+  llvm::SmallSet<VarDecl *, 8> knownStoredProperties;
+  auto addStoredProperty = [&](VarDecl *var) {
+    if (!var->isStatic() && var->hasStorage()) {
+      if (knownStoredProperties.insert(var).second)
+        _addStoredProperty(var);
+    }
+  };
+
   // If we have a distributed actor, find the id and actorSystem
   // properties. We always want them first, and in a specific
   // order.
-  VarDecl *distributedActorId = nullptr;
-  VarDecl *distributedActorSystem = nullptr;
   if (decl->isDistributedActor()) {
+    VarDecl *distributedActorId = nullptr;
+    VarDecl *distributedActorSystem = nullptr;
     ASTContext &ctx = decl->getASTContext();
     for (auto *member : implDecl->getMembers()) {
       if (auto *var = dyn_cast<VarDecl>(member)) {
@@ -201,17 +210,14 @@ static void enumerateStoredPropertiesAndMissing(
 
   for (auto *member : implDecl->getMembers()) {
     if (auto *var = dyn_cast<VarDecl>(member)) {
-      if (!var->isStatic() && var->hasStorage()) {
-        // Skip any properties that we already emitted explicitly
-        if (var == distributedActorId)
-          continue;
-        if (var == distributedActorSystem)
-          continue;
-
-        addStoredProperty(var);
-      }
+      addStoredProperty(var);
     }
 
+    member->visitAuxiliaryDecls([&](Decl *auxDecl) {
+      if (auto auxVar = dyn_cast<VarDecl>(auxDecl))
+        addStoredProperty(auxVar);
+    });
+
     if (auto missing = dyn_cast<MissingMemberDecl>(member))
       if (missing->getNumberOfFieldOffsetVectorEntries() > 0)
         addMissing(missing);

test/Macros/Inputs/syntax_macro_definitions.swift

@@ -408,6 +408,29 @@ extension PropertyWrapperMacro: AccessorMacro, Macro {
   }
 }
 
+extension PropertyWrapperMacro: PeerMacro {
+  public static func expansion(
+    of node: AttributeSyntax,
+    providingPeersOf declaration: some DeclSyntaxProtocol,
+    in context: some MacroExpansionContext
+  ) throws -> [DeclSyntax] {
+    guard let varDecl = declaration.as(VariableDeclSyntax.self),
+      let binding = varDecl.bindings.first,
+      let identifier = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier,
+      binding.accessor == nil,
+      let type = binding.typeAnnotation?.type
+    else {
+      return []
+    }
+
+    return [
+      """
+      var _\(raw: identifier.trimmedDescription): MyWrapperThingy<\(type)>
+      """
+    ]
+  }
+}
+
 public struct WrapAllProperties: MemberAttributeMacro {
   public static func expansion(
     of node: AttributeSyntax,

test/Macros/macro_expand_peers.swift

@@ -124,6 +124,9 @@ struct Main {
     }
     print(result2)
     // CHECK-EXEC: hahaha global
+
+    // CHECK-EXEC: MyWrapperThingy<Swift.Int>(storage: 5)
+    print(S3(x: 5))
   }
 }
 
@@ -152,3 +155,36 @@ struct S2 {
   }
   #endif
 }
+
+// Stored properties generated by a peer macro
+@attached(accessor)
+@attached(peer, names: prefixed(_))
+macro myPropertyWrapper() =
+    #externalMacro(module: "MacroDefinition", type: "PropertyWrapperMacro")
+
+struct Date { }
+
+struct MyWrapperThingy<T> {
+  var storage: T
+
+  var wrappedValue: T {
+    get {
+      print("Getting value \(storage)")
+      return storage
+    }
+
+    set {
+      print("Setting value \(newValue)")
+      storage = newValue
+    }
+  }
+}
+
+struct S3 {
+  @myPropertyWrapper
+  var x: Int = 0
+
+  init(x: Int) {
+    self._x = MyWrapperThingy(storage: x)
+  }
+}